Cardiac tachy arrhythmia therapy selection based on patient response information

ABSTRACT

Cardiac treatment methods and devices providing templates representative of past tachyarrhythmia events, each template associated with a therapy. A cardiac waveform is detected, and if it corresponds to a particular template associated with a previous therapy that was satisfactory in terminating a past event, the previous therapy is delivered again. If unsatisfactory, the previous therapy is eliminated as an option. If, for example, the previous therapy was an antitachycardia pacing therapy unsatisfactory in terminating the past tachyarrhythmia event, delivery of the antitachycardia pacing therapy is eliminated as an option. Instead of ATP therapy, one or more of a cardioversion, defibrillation, or alternate anti-tachycardia pacing therapy may be associated with the particular template. Cardiac waveforms and templates may correspond in terms of one or more of morphology, timing, drug regimen, medication, neural activity, patient activity, hemodynamic status, cardiac tissue impedance, transthoracic impedance, or other information corresponding to the episode.

RELATED PATENT DOCUMENTS

This application is a continuation of U.S. patent application Ser. No.10/995,655 filed on Nov. 23, 2004, to issue as U.S. Pat. No. 7,228,173on Jun. 5, 2007, to which Applicant claims priority under 35 U.S.C.§120, and which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to patient internal medicaldevices and methods and, more particularly, to patient internal medicaldevices and methods that select tachyarrhythmia therapy based onprevious patient therapy responses.

BACKGROUND OF THE INVENTION

Proper cardiac function relies on the synchronized contractions of theheart at regular intervals. When the heart is functioning normally,synchronized cardiac contractions are initiated at the sinoatrial nodeand the heart is said to be operating in normal sinus rhythm. However,if contractions of the heart become irregular or uncoordinated, or ifthe contraction rate is too fast or too slow, the heart rhythm isdescribed as arrhythmic. Cardiac arrhythmia may be caused, for example,by disease processes or from aberrant electrical conduction patternsoccurring in the heart tissue. Cardiac arrhythmia impairs cardiacpumping efficiency and some types of cardiac arrhythmia can be lifethreatening.

A cardiac arrhythmia that originates in an atrial region of the heart isdenoted a supra-ventricular tachyarrhythmia (SVT). Atrial fibrillationand atrial flutter are examples of SVT. Both conditions arecharacterized by rapid, uncoordinated contractions of the atriaresulting in hemodynamically inefficient pumping action.

Another example of SVT is sinus tachycardia, which is an increased heartrate due to exercise or a quick emotional response. In contrast toatrial fibrillation and atrial flutter, sinus tachycardia ischaracterized by rapid, coordinated contractions of the atria resultingin hemodynamically efficient pumping action, compensating for theincreased strain placed upon the body during exercise or quick emotionalresponses. Whereas atrial fibrillation and atrial flutter are “abnormal”(yet not lethal), sinus tachycardia is “normal” (and also not lethal).

Cardiac arrhythmias originating in a ventricular region of the heart aredenoted ventricular tachyarrhythmias. Ventricular tachycardia (VT) ischaracterized by rapid ventricular contractions and can degenerate intoventricular fibrillation (VF). Ventricular fibrillation producesextremely rapid, non-coordinated contractions of the ventricles.Ventricular fibrillation is fatal unless the heart is returned to sinusrhythm within a few minutes.

Implantable cardiac rhythm management (CRM) devices, includingpacemakers and implantable cardioverter/defibrillators, have been usedto deliver effective treatment to patients with serious cardiacarrhythmias. Cardiac rhythm management devices may treat cardiacarrhythmias with a variety of tiered therapies. These tiered therapiesrange from delivering low energy pacing pulses timed to assist the heartin maintaining pumping efficiency to providing high-energy shocks totreat and/or terminate fibrillation. To effectively deliver thesetreatments, the CRM must first identify the type of arrhythmia that isoccurring, after which appropriate therapy may be delivered to theheart.

SUMMARY OF THE INVENTION

The present invention is directed to methods and systems for selectingtachyarrhythmia therapy based on previous patient therapy responses.Methods in accordance with the present invention involve providing oneor more templates representative of one or more of a patient's pasttachyarrhythmia events, each of the templates associated with a therapyto treat tachyarrhythmia events. A cardiac waveform is detected, and ifthe cardiac waveform corresponds to a particular template of the one ormore templates, a determination is made to see if a previous therapyassociated with the particular template was satisfactory in terminatinga past tachyarrhythmia event. If the previously delivered therapy wasdetermined satisfactory, the previous therapy is delivered again. If thepreviously delivered therapy was determined unsatisfactory, the previoustherapy is eliminated as an option for treating a subsequenttachyarrhythmia event associated with the particular template.

In further embodiments, if the previous therapy was an antitachycardiapacing therapy determined to be unsatisfactory in terminating the pasttachyarrhythmia event, delivery of the antitachycardia pacing therapyfor treating a subsequent tachyarrhythmia event is eliminated as anoption. Instead of ATP therapy, one or more of a cardioversion, adefibrillation therapy, or an alternate anti-tachycardia pacing therapymay be associated with the particular template.

The correspondence between the cardiac waveform and the particulartemplate may be a correspondence in terms of one or more of morphology,timing, drug regimen, medication information, neural activityinformation, patient activity information, hemodynamic statusinformation, cardiac tissue impedance information, transthoracicimpedance information, respiratory information (e.g., patient disorderedbreathing information), or other information corresponding to theepisode.

A new template may be added to the one or more templates by replacing anoldest template of the one or more templates with the new template. Aparticular template may be deleted if the particular template is olderthan a predetermined age, or has not corresponded to a cardiac waveformfor a predetermined time, or has corresponded to past arrhythmias lessfrequently relative to other templates, or represents a heart-ratesimilar to other existing templates. A particular template may also bedeleted if the particular template is associated with a drug regimenthat no longer matches the patient's current drug regimen.

The detected cardiac waveform may be indicative of an arrhythmia in theventricles, of ventricular or supra-ventricular origin, or may beindicative of an arrhythmia in the atria. Arbitrating between two ormore templates may be done if the cardiac waveform corresponds to two ormore templates. Arbitration may involve: selecting a most recently usedor generated template associated with a treatment satisfactory interminating the past tachyarrhythmia event, and delivering itsassociated tachyarrhythmia therapy; selecting a template of the two ormore templates associated with a treatment satisfactory in terminatingthe past tachyarrhythmia event, and delivering its associatedtachyarrhythmia therapy; selecting the most frequently matched templateassociated with a treatment satisfactory in terminating the pasttachyarrhythmia event, and delivering its associated tachyarrhythmiatherapy; selecting the template associated with a treatment satisfactoryin terminating the past tachyarrhythmia event whose rate informationmost closely corresponds to the detected cardiac waveform, anddelivering its associated tachyarrhythmia therapy; and/or selecting thetemplate associated with one or more of a patient's drug regimen, neuralactivity, patient activity, hemodynamic state, transthoracic impedance,and cardiac tissue impedance similar to the patient's current status. Anew therapy may be associated with the particular template if theprevious therapy was unsatisfactory, including an anti-tachycardiapacing therapy of substantially equivalent aggression in terms of energyor coupling interval, an anti-tachycardia pacing therapy of greateraggression in terms of energy or coupling interval, and/or acardioversion or defibrillation therapy.

Further embodiments in accordance with the present invention involveproviding one or more templates representative of one or more of apatient's past tachyarrhythmia events, each of the templates associatedwith a therapy delivered to treat a past tachyarrhythmia event, the oneor more templates including a low-rate template. A cardiac waveform isdetected, and a determination is made that the cardiac waveform isindicative of a high-rate tachyarrhythmia event having one or both of amorphology and timing corresponding to the low-rate template. If thedelivered therapy associated with the low-rate template was satisfactoryin terminating the past tachyarrhythmia event associated with thelow-rate template, it is delivered again to treat the high-ratetachyarrhythmia event. If the delivered therapy associated with thelow-rate template was unsatisfactory in terminating the past ventriculartachyarrhythmia event, a therapy different from the therapy associatedwith the low-rate template is delivered instead.

Other embodiments in accordance with the present invention include amedical system having a cardiac therapy system configured to deliver acardiac therapy to a patient. A detector system is configured to detecta cardiac waveform associated with a tachyarrhythmia, and a templateprocessor, coupled to the detector system and the cardiac therapysystem, is configured to provide one or more templates representative ofone or more of a patient's past tachyarrhythmia events. Each of thetemplates is associated with a therapy to treat tachyarrhythmia events,and, if the cardiac waveform corresponds to a particular template, thetemplate processor is configured to determine if a previous therapyassociated with the particular template was satisfactory in terminatinga past tachyarrhythmia event. If the previous therapy was determinedsatisfactory, the template processor prompts the cardiac therapy systemto deliver the previous therapy. If the previous therapy was determinedunsatisfactory, the previous therapy is eliminated as an option fortreating a subsequent tachyarrhythmia event associated with theparticular template, and the cardiac therapy system is prompted todeliver a different therapy. The cardiac therapy system may beconfigured to deliver an anti-tachycardia pacing therapy to the patientto treat the tachyarrhythmia and determine one or both of theeffectiveness and satisfaction of the anti-tachycardia pacing therapy.

Further, a patient activity sensor may be configured to provide patientactivity information associated with tachyarrhythmia episodes to thetemplate processor. In other embodiments, a neural activity sensor isconfigured to provide patient neural activity information associatedwith tachyarrhythmia episodes to the template processor. In stillfurther embodiments, a transthoracic impedance sensor is configured toprovide patient transthoracic impedance information associated withtachyarrhythmia episodes to the template processor. In yet otherembodiments, an accelerometer is configured to provide accelerationinformation associated with tachyarrhythmia episodes to the templateprocessor. A cardiac tissue impedance sensing system may be configuredto provide patient cardiac tissue impedance information associated withtachyarrhythmia episodes to the template processor. A hemodynamic statussensor may be configured to provide patient hemodynamic statusinformation associated with tachyarrhythmia episodes.

The above summary of the present invention is not intended to describeeach embodiment or every implementation of the present invention.Advantages and attainments, together with a more complete understandingof the invention, will become apparent and appreciated by referring tothe following detailed description and claims taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial view of one embodiment of an implantable medicaldevice that may be used to implement therapy selection using patientresponse history in accordance with embodiments of the invention;

FIG. 2 is a block diagram illustrating functional components of animplantable medical device with which therapy selection using patientresponse history may be implemented in accordance with embodiments ofthe present invention;

FIG. 3 is a graph illustrating a cardiac signal having cardiac waveformfeatures useful for template creation in accordance with embodiments ofthe invention;

FIG. 4 is a flowchart of a method of therapy selection using patientresponse information in accordance with embodiments of the presentinvention;

FIG. 5 is a flowchart illustrating a method of template selection andgeneration for therapy selection using patient response information inaccordance with embodiments of the invention;

FIG. 6 is a flow chart illustrating a method of determining patienttherapy response information in accordance with embodiments of theinvention;

FIG. 7 is a block diagram illustrating determination of patient therapyresponse information in accordance with embodiments of the invention;

FIG. 8 is a flow chart illustrating a method of initializing templatesin accordance with embodiments of the invention; and

FIG. 9 is a block diagram of a medical system that may be used toimplement arrhythmia therapy selection using patient therapy responseinformation and other patient information in accordance with embodimentsof the present invention.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail below. It is to be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the invention isintended to cover all modifications, equivalents, and alternativesfalling within the scope of the invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

In the following description of the illustrated embodiments, referencesare made to the accompanying drawings forming a part hereof, and inwhich are shown by way of illustration, various embodiments by which theinvention may be practiced. It is to be understood that otherembodiments may be utilized, and structural and functional changes maybe made without departing from the scope of the present invention.

Some current medical devices discriminate between supra-ventriculartachycardias (SVT) and ventricular tachycardias (VT) using cardiacwaveform templates. Such devices typically detect a cardiac episode, andcompare the episode in question to a normal sinus rhythm (NSR) templateusing an algorithm that determines a correspondence between episodeinformation and template information. If the episode corresponds withthe NSR template, the episode is diagnosed as SVT tachycardia, andtherapy is withheld. In contrast, if the episode does not correspondwith the NSR template, processes are typically performed to diagnose andverify the episode as ventricular tachycardia, after which therapy maybe delivered. In current devices, the particular type of therapydelivered must be decided upon and programmed into the device in advanceby the physician. Furthermore, if it is found that a particular type oftherapy is not suitable for a patient, the physician must re-program thedevice during a follow-up visit such that a different type of therapy isdelivered for treating the patient's subsequent ventriculartachycardias.

Some current medical devices can treat a VT by delivering a high-energy,painful shock or a low-energy, pain-free burst of anti-tachycardiapacing (ATP). Many physicians program these devices to deliver shocksfor high-rate VT and reserve ATP for low-rate VT and fast atrialrhythms, such as atrial flutter. However, ATP may be safe and effectivefor treating high-rate VT, as well.

Furthermore, studies have shown that, for those patients for whom ATPsuccessfully converts their first VT, there is a 99% probability thatATP will successfully convert their subsequent VTs. In contrast, studieshave shown that, for those patients for whom ATP does not convert theirfirst VT, the probability of ATP efficacy for subsequent VTs drops toonly 38%.

Embodiments of methods and devices in accordance with the presentinvention may be implemented to adapt to changing patient conditions,medications, and/or cardiac pathology over time. Adaptation over timemay possibly decrease the time to effective therapy, and increases theratio of pain-free to painful therapy, by automatically incorporatinginformation about that patient's prior therapy efficacy when decidingwhat type of therapy, if any, should be delivered to the currenttachyarrhythmia episode.

In various embodiments, cardiac beats may be analyzed by examining themorphology of the electrical cardiac signal waveform. For example, acardiac beat may be classified as a normal beat, e.g., a normallyconducted SVT rhythm, by comparing the cardiac signal waveform to atemplate characterizing a normal beat. If the cardiac signal waveform isconsistent with the template, the cardiac beat may be classified asnormal. Similarly, a sensed abnormal or arrhythmic cardiac beat may beclassified by comparing the abnormal cardiac signal waveform to one ormore templates characterizing an abnormal beat experienced by thepatient in the past. The beat may be classified as abnormal if the beatwaveform does not match or correspond to a normal beat template and/orif the beat waveform matches or corresponds to an abnormal beattemplate. Such comparisons may be used to determine that the sensedcardiac beat is abnormal as well as to assess the type of abnormality.

A cardiac waveform template may be created and used to analyze orotherwise process a sensed cardiac signal for a variety of purposes,including, for example, arrhythmia prediction or detection. Cardiactemplates may include representative waveforms and/or informationderived from waveforms, such as various attributes and/or ranges ofattributes of the sensed cardiac signal, including, but not limited to:timing and/or rate information, changes in QRS width, T-wave amplitude,Q-wave amplitude, QT interval, R-R intervals, interval statistics, orother intervals or attributes useful for determining a correspondencebetween a cardiac waveform and a template. A cardiac waveform templatemay be formed, for example, by identifying one or more cardiac waveformfeatures representative of a particular cardiac beat morphology. Theparticular waveform features may include morphological features such ascritical points, significant points, curvature, local extrema,inflection points, rise or fall times, slopes, areas above and/or belowbaselines, and frequency and/or wavelet coefficients, or the like.

In addition to cardiac waveform features, such as waveform morphology,templates in accordance with the present invention may include otherinformation. Patient history to previous therapy, indicating theefficacy of previous therapy attempts for arrhythmias corresponding to agiven template, may also be included. Further, other patientinformation, such as patient activity levels, accelerometer information,hemodynamic status (e.g., blood pressure and blood oxygen level),cardiac tissue impedance, neural activity information, transthoracicimpedance, pharmacological agent type and/or level information,respiratory information (e.g., patient disordered breathinginformation), or other patient information may be associated with acardiac waveform template in accordance with the present invention.Pharmacological agent type and/or level information may include a changein medications prescribed by a physician, which may alter a patient'sheart rhythms, and may require adapting one or more templates to thepatient's altered rhythms.

Providing this additional information as a part of the cardiac waveformtemplate enables automated re-programming of implantable medical deviceson an episode-by-episode basis, and/or in response to patient-relatedchanges, such as a change in a patient's medication or follow-up from aphysician. Information such as medication change information may beprovided to an implantable medical device using an advanced patientmanagement system, as will be further described below. Furtherdescription of cardiac waveform templates and template initiation, andupdating devices and methodologies are further described in commonlyowned U.S. Publication No. 2006/0074331, and U.S. Pat. Nos. 6,708,058,and 6,449,503, which are hereby incorporated herein by reference.Further description of methods and devices for determining or acquiringinformation that may be associated with templates in accordance with thepresent invention are described in commonly owned U.S. Publication Nos.2003/0125774, 2003/0130581, 2005/0042589, and 2005/0065572, which arehereby incorporated herein by reference.

It is understood that the devices and methodologies in accordance withthe present invention described with reference to ventriculartachycardia and VT templates are similarly applicable to atrialtachycardia and atrial tachycardia templates, as well as SVT/NSR andSVT/NSR templates. For SVT templates and NSR templates, the therapyassociated with the template may be “none” or “withhold therapy” forexample. For simplicity of explanation, and not of limitation, thedescription of devices and methodologies provided herein will generallybe made in the context of ventricular tachycardia and VT templates.

Consider, for example, a device configured to treat VT. Once it has beenconfirmed that a patient has experienced at least one true VT, one ormore VT templates may be generated from the prior VT episodes. A VTtemplate may include timing and morphology information, as well asinformation regarding the type and efficacy of therapy used to treat theprior VT from which the template was generated. The device may use theVT template(s) to automate selection of a therapy for subsequent VTscorresponding to the template(s).

Embodiments of methods and devices in accordance with the presentinvention may automate this re-programming on an episode-by-episodebasis. An episode in question is first compared to one or more templatesindicative of a normal supra-ventricular conducted beat, such as an NSRtemplate and/or a template indicative of fast ventricular rhythmsoriginating in the patient's atria. If the episode corresponds to theNSR template and/or the fast atrial-originated template, it is diagnosedas SVT tachycardia (SVT) and therapy is withheld.

However, if the episode does not correspond with the one or moretemplates indicative of the patient's normal rhythms, the episode isthen compared to the VT template(s) created from the patient's prior VTepisode(s). If the current episode corresponds with any one of the VTtemplates, the device then checks the VT template to see if the therapydelivered to the prior VT was satisfactory. If the prior therapy wassatisfactory, that same type of therapy is delivered to the currentepisode, regardless of the rate of the current episode.

In this way, ATP can be delivered to high-rate VTs if ATP was effectiveat treating similar low-rate VTs in the past. If, however, the therapydelivered to the prior VT was not effective and/or satisfactory, then adifferent or more aggressive therapy is delivered to the currentepisode. In this way, the time to effective and/or satisfactorytreatment is shortened, as the device does not attempt to use aparticular ATP therapy to treat a VT if that ATP therapy was noteffective and/or satisfactory at treating similar VTs in the past. Thetime to effective treatment may be significantly shortened in accordancewith an approach that does not attempt to use any type of ATP therapy totreat a VT if a prior ATP therapy was not effective and/or satisfactoryat treating similar VTs in the past. In this approach, the device mayimmediately deliver a cardioversion or defibrillation therapy. In analternate approach, a particular ATP therapy may be eliminated as anoption for treatment if it was not satisfactory, and other ATP therapiesmay be attempted for subsequent events.

Embodiments of the present system illustrated herein are generallydescribed as being implemented in a patient internal medical device(PIMD), which may operate in numerous cardioversion/defibrillation andpacing modes known in the art. Various types of single and multiplechamber PIMDs may be used to implement a number of pacing therapies asare known in the art, in addition to cardioversion/defibrillationtherapies. A PIMD may implement various anti-tachyarrhythmia therapies,such as tiered anti-tachyarrhythmia therapies, which may involveperforming rate-based and/or morphological tachyarrhythmiadiscrimination analyses.

It is understood that configurations, features, and combination offeatures described in the present disclosure can be implemented in awide range of implantable or external medical devices, and that suchembodiments and features are not limited to the particular devicesdescribed herein. The systems and methods described herein may beimplemented in a wide variety of implantable or external diagnosticand/or therapeutic cardiac devices such as defibrillators,cardioverters, pacemakers, cardiac monitors, and resynchronizers, forexample.

Although the present system is described in conjunction with animplantable cardiac defibrillator having a microprocessor-basedarchitecture, it will be understood that the implantable cardiacdefibrillator (or other device) may be implemented in any logic-basedintegrated circuit architecture, if desired.

In one embodiment, the cardiac rhythm management system is animplantable cardioverter/defibrillator configured as a single chamberdevice that operates to process cardiac waveforms according to atemplate methodology in accordance with the principles of the presentinvention. In another embodiment, the cardiac rhythm management systemis an implantable cardioverter/defibrillator that is configured as adual chamber device. In yet another embodiment, the cardiac rhythmmanagement system is an implantable cardioverter/defibrillatorconfigured to sense and/or provide electrical stimulation to multipleheart chambers, for example, both ventricles of the heart, as in aresynchronizer used to treat congestive heart failure (CHF).

Referring now to FIG. 1 of the drawings, there is shown one embodimentof a cardiac rhythm management system that may be used to implementtachyarrhythmia therapy selection methods of the present invention. Thecardiac rhythm management system in FIG. 1 includes a PIMD 100electrically and physically coupled to a lead system 110. The housingand/or header of the PIMD 100 may incorporate one or more electrodes198, 109 used to provide electrical stimulation energy to the heart andto sense cardiac electrical activity. The PIMD 100 may utilize all or aportion of the PIMD housing as a can electrode 109. The PIMD 100 mayinclude an indifferent electrode 198 positioned, for example, on theheader or the housing of the PIMD 100. If the PIMD 100 includes both acan electrode 109 and an indifferent electrode 198, the electrodes 198,109 typically are electrically isolated from each other. The PIMD 100may also include an accelerometer 130 that may provide patient activityinformation and/or movement information.

The lead system 110 is used to detect electric cardiac signals producedby the heart 190 and to provide electrical energy to the heart 190 undercertain predetermined conditions to treat cardiac arrhythmias. The leadsystem 110 may include one or more electrodes used for pacing, sensing,and/or defibrillation. In the embodiment shown in FIG. 1, the leadsystem 110 includes an intracardiac right ventricular (RV) lead system104, an intracardiac right atrial (RA) lead system 105, an intracardiacleft ventricular (LV) lead system 106, and an extracardiac left atrial(LA) lead system 108. The lead system 110 of FIG. 1 illustrates oneembodiment that may be used in connection with the tachyarrhythmiatherapy selection methodologies described herein. Other leads and/orelectrodes may additionally or alternatively be used. For example, thelead system 110 may include electromyogram sensors, electroencephalogramsensors, or other sensors as desired.

The lead system 110 may include intracardiac leads 104, 105, 106implanted in a human body with portions of the intracardiac leads 104,105, 106 inserted into a heart 190. The intracardiac leads 104, 105, 106include various electrodes positionable within the heart for sensingelectrical activity of the heart and for delivering electricalstimulation energy to the heart, for example, pacing pulses and/ordefibrillation shocks to treat various arrhythmias of the heart.

As illustrated in FIG. 1, the lead system 110 may include one or moreextracardiac leads 108 having electrodes, e.g., epicardial electrodes,positioned at locations outside the heart for sensing and/or pacing oneor more heart chambers.

The right ventricular lead system 104 illustrated in FIG. 1 includes anSVC-coil 116, an RV-coil 114, an RV-ring electrode 111, and an RV-tipelectrode 112. The right ventricular lead system 104 extends through theright atrium 120 and into the right ventricle 119. In particular, theRV-tip electrode 112, RV-ring electrode 111, and RV-coil electrode 114are positioned at appropriate locations within the right ventricle forsensing and delivering electrical stimulation pulses to the heart. TheSVC-coil 116 is positioned at an appropriate location within the rightatrium chamber of the heart 190 or a major vein leading to the rightatrial chamber of the heart 190.

In one configuration, the RV-tip electrode 112 referenced to the canelectrode 109 may be used to implement unipolar pacing and/or sensing inthe right ventricle. Bipolar pacing and/or sensing in the rightventricle may be implemented using the RV-tip 112 and RV-ring 111electrodes. For example, a tip-to-ring vector may be used todiscriminate between VT and SVT, such as by using a template having arange of expected values of characteristics of signals sensed using thisvector in some devices. In other devices, the tip-to-ring vector and theRV-coil to SVC-coil/can vector may be used to discriminate between VTand SVT. (For example, where the SVC-coil is electrically tied to thecan.) In yet another configuration, the RV-ring 111 electrode mayoptionally be omitted, and bipolar pacing and/or sensing may beaccomplished using the RV-tip electrode 112 and the RV-coil 114, forexample. The right ventricular lead system 104 may be configured as anintegrated bipolar pace/shock lead. The RV-coil 114 and the SVC-coil 116are defibrillation electrodes.

The left ventricular lead 106 includes an LV distal electrode 113 and anLV proximal electrode 117 located at appropriate locations in or aboutthe left ventricle for pacing and/or sensing the left ventricle. Theleft ventricular lead 106 may be guided into the right atrium of theheart via the superior vena cava. From the right atrium, the leftventricular lead 106 may be deployed into the coronary sinus ostium, theopening of the coronary sinus. The lead 106 may be guided through thecoronary sinus to a coronary vein 124 of the left ventricle. This veinis used as an access pathway for leads to reach the surfaces of the leftventricle that are not directly accessible from the right side of theheart. Lead placement for the left ventricular lead 106 may be achievedvia subclavian vein access and a preformed guiding catheter forinsertion of the LV electrodes 113, 117 adjacent to the left ventricle.

Unipolar pacing and/or sensing in the left ventricle may be implemented,for example, using the LV distal electrode 113 referenced to the canelectrode 109. The LV distal electrode 113 and the LV proximal electrode117 may be used together as bipolar sense and/or pace electrodes for theleft ventricle. The left ventricular lead 106 and the right ventricularlead 104, in conjunction with the PIMD 100, may be used to providecardiac resynchronization therapy such that the ventricles of the heartare paced substantially simultaneously, or in phased sequence, toprovide enhanced cardiac pumping efficiency for patients suffering fromchronic heart failure.

The right atrial lead 105 includes an RA-tip electrode 156 and anRA-ring electrode 154 positioned at appropriate locations in the rightatrium for sensing and pacing the right atrium. In one configuration,the RA-tip 156 referenced to the can electrode 109, for example, may beused to provide unipolar pacing and/or sensing in the right atrium 120.In another configuration, the RA-tip electrode 156 and the RA-ringelectrode 154 may be used to effect bipolar pacing and/or sensing.

FIG. 1 illustrates one embodiment of a left atrial lead system 108. Inthis example, the left atrial lead 108 is implemented as an extracardiaclead with an LA distal electrode 118 positioned at an appropriatelocation outside the heart 190 for sensing and pacing the left atrium.Unipolar pacing and/or sensing of the left atrium may be accomplished,for example, using the LA distal electrode 118 to the can 109 pacingvector. The left atrial lead 108 may be provided with additionalelectrodes used to implement bipolar pacing and/or sensing of the leftatrium.

Referring now to FIG. 2, there is shown a block diagram of an embodimentof a CRM system 200 employing a PIMD 260 suitable for implementingtherapy selection methodologies of the present invention. FIG. 2 showsthe CRM system 200 divided into functional blocks. There exist manypossible configurations in which these functional blocks can bearranged. The example depicted in FIG. 2 is one possible functionalarrangement. The CRM system 200 includes circuitry for receiving cardiacsignals from a heart and delivering electrical energy in the form ofpace pulses or cardioversion/defibrillation pulses to the heart.

A cardiac lead system 210 may be implanted so that cardiac electrodescontact heart tissue as described above in connection with FIG. 1. Thecardiac electrodes of the lead system 210 sense cardiac signalsassociated with electrical activity of the heart. The sensed cardiacsignals may be transmitted to a PIMD 260 through the lead system 210.The cardiac electrodes and lead system 210 may be used to deliverelectrical stimulation generated by the PIMD 260 to the heart tomitigate various cardiac arrhythmias. The PIMD 260, in combination withthe cardiac electrodes and lead system 210, may detect cardiac signalsand deliver therapeutic electrical stimulation to any of the left andright ventricles and left and right atria, for example. A can electrode205 coupled to a housing of the PIMD 260 may additionally be used tosense cardiac signals and deliver electrical stimulation to the heart.

In one embodiment, PIMD circuitry 201 is encased in a hermeticallysealed housing suitable for implanting in a human body. Power issupplied by an electrochemical battery 230 that is housed within thePIMD 260. In one embodiment, the PIMD circuitry 201 is a programmablemicroprocessor-based system, including a control system 250, sensingcircuit 220, pacing therapy circuit 215, shock therapy circuit 225, andmemory 240. The memory 240 may be used, for example, to store templateinformation, parameters for various pacing, defibrillation, and sensingmodes, and data associated with sensed cardiac signals or otherinformation. The parameters and data stored in the memory 240 may beused on-board for various purposes and/or transmitted via telemetry toan external programmer unit 245 or other patient-external device, asdesired.

The control system 250 maybe used to control various subsystems of thePIMD 260, including the pacing therapy circuit 215, the shock therapycircuitry 225, and the sensing circuitry 220. The control system 250 mayalso include a template processor 255 for implementing a templateinitiation, template generation, template updating, and methodologiesfor therapy selection according to embodiments of the invention.

Communications circuitry 235 allows the PIMD 260 to communicate with anexternal programmer unit 245 and/or other patient-external system(s). Inone embodiment, the communications circuitry 235 and the programmer unit245 use a wire loop antenna and a radio frequency telemetric link toreceive and transmit signals and data between the programmer 245 andcommunications circuitry 235. In this manner, programming commands maybe transferred to the PIMD 260 from the programmer 245 during and afterimplant. In addition, stored cardiac data may be transferred to theprogrammer unit 245 from the PIMD 260, for example.

Sensing circuitry 220 detects cardiac signals sensed at the cardiacelectrodes 210. The sensing circuitry may include, for example,amplifiers, filters, A/D converters, and other signal processingcircuitry. Cardiac signals processed by the sensing circuitry may becommunicated to the control system 250 and to the template processor255.

The control system 250 is coupled to the template processor 255 and usestemplates 30 created and maintained by the template processor 255 toperform various functions, including, for example, arrhythmia analysisand therapy selection. An arrhythmia analysis section of the controlsystem 250 may compare cardiac signals detected through the sensingcircuitry 220 to the templates created and maintained by the templateprocessor 255 to detect or predict various cardiac arrhythmias, and toassist selection of appropriate therapies for the patient.

The pacing therapy circuit 215 is controlled by a pacemaker in thecontrol system 250 and may be used to deliver pacing stimulation pulsesto the heart through one or more of the cardiac electrodes, according toa pre-established pacing regimen under appropriate conditions. Also, thepacing therapy circuit 215 may deliver ATP therapy in response to VTsthat correspond to templates associated with ATP.

The shock therapy circuit 225 and pacing therapy circuit 215 are coupledto an arrhythmia analysis section of the control system 250. The shocktherapy circuit 225 may be used to deliver high-energy electricalstimulation to the heart to terminate or mitigate cardiac arrhythmiassuch as atrial or ventricular tachycardia or fibrillation detected orpredicted by the control system 250 when patient history suggests thatATP is not effective and/or satisfactory, and/or when a template doesnot correspond to a cardiac episode.

The PIMD 260 may optionally be coupled to a display device 270 capableof displaying various information related to template creation andmaintenance, and/or cardiac rhythm analysis using morphologicaltemplates, as well as other information. For example, the display device270 may depict a graphical display of one or more detected cardiacwaveforms along with the templates used to analyze or classify thedetected cardiac waveforms. The display may show various data regardingthe number of templates used by the PIMD, including, for example,statistics relating to the frequency particular templates were used toanalyze or classify cardiac waveforms. Other uses for the display inconnection with the template creation and adjustment methods of theinvention are also possible.

FIG. 3 illustrates a particular beat's morphology useful for templatecreation and correspondence in accordance with embodiments of theinvention. The template may include one or more attributescharacterizing a cardiac waveform representative of the particular beatmorphology, for example. As illustrated in FIG. 3, a cardiac waveform310 representing a particular beat morphology is sensed and occurrencesof one or more cardiac waveform features 320 are detected. A waveformfeature 320 may include a particular point of a cardiac signal waveform310. The waveform features 320 may be identified based on variousmorphological aspects of the cardiac waveform, such as critical points,local extrema, inflection points, rise or fall times, slopes, areasabove and/or below a baseline, and frequency and/or waveletcoefficients, or by other aspects, as is known in the art.

FIG. 4 is a flowchart of a method 400 of therapy selection using patientresponse information in accordance with embodiments of the presentinvention. The method 400 begins with an episode 410 being detected. Theepisode 410 may be, for example, a rate-based or other anomaly for whichdiscrimination is desired. Information from the episode corresponds totemplates 420. The information may be a cardiac waveform encompassing aseries of beats sensed from one or more electrodes, a portion of acardiac waveform, a portion of a beat, or attributes from a cardiacwaveform, as well as other information such as patient information. Asan example, useful for illustrative purposes but not limiting, considerthat morphological features correspond 430 to at least one of thetemplates 420, indicating that the episode 410 is an arrhythmia. Thetemplate 420 that corresponds to the episode 410 is then used todetermine if a previous therapy was satisfactory in treating thearrhythmia. Correspondence to a template may be determined by, forexample, correlation, convolution, and/or statistical analysis ofcardiac waveform information.

If a previous therapy was satisfactory, for example if the templateindicates that ATP was satisfactory in treating the last arrhythmia thatcorresponded to the template 420, then the previous therapy is delivered460 again. If the previous therapy attempt 450 was not satisfactory, forexample if the template indicates that ATP was not satisfactory intreating the last arrhythmia that corresponded to the template 420 or ifthe previous therapy accelerated the cardiac rhythm, then a differentand/or more aggressive therapy 470 is delivered. If no templates 420 arefound to correspond to 430 the current episode, then a new template maybe created 440, as will be described in more detail below. Whether ornot a particular therapy was satisfactory may be based upon one or moreof a variety of factors, including: if the therapy was effective, if thetherapy didn't take too long, if the therapy didn't cause unnecessarypain, if the therapy didn't require unnecessary energy, and/or othersubjective and/or objective factors.

FIG. 5 is a flow chart illustrating a method 500 of template selectionand generation for therapy selection using patient response informationin accordance with embodiments of the invention. According to thisembodiment, an initial template list comprising a list of templatesrepresentative of various cardiac beat morphologies and/orcharacteristics may optionally be established 510. Alternatively, newtemplates may be formed without an initial template list using theprocesses described below.

A ventricular tachycardia is sensed 520 using a cardiac waveform signal.The waveform features of the cardiac signal are detected 530 andcompared 540 to each template in the template list, if any. If apredetermined number of the detected features of the cardiac waveformfall within the target ranges of the template, e.g., six of sevencardiac waveform features fall within target ranges of the template, thecardiac waveform may be classified as matching or corresponding 550 tothe template. The template may then be used for therapy selection 560,based on patient therapy history information associated with thetemplate, as described above.

If the detected waveform features do not correspond 550 to a template,the waveform features are compared to the next template until alltemplates have been compared 555 to the cardiac waveform features. Ifnone of the templates correspond to the cardiac waveform features, a newtemplate may be created 570 by, for example, extracting features of thecardiac waveform for correspondence purposes with future sensedepisodes, and then associating therapy effectiveness and/or satisfactioninformation as therapy is delivered to the current episode. Otherinformation may also be associated with the template, such as patientmedication levels, patient activity information, and other sensorinformation measured at or near the time the arrhythmia occurred thatmay provide improved discrimination for therapy delivery selection.

FIG. 6 is a flow chart illustrating a method 600 of determining patienttherapy response information, such as therapy effectiveness and/orwhether or not the therapy was satisfactory, in accordance withembodiments of the invention. The method 600 begins with an episodebeing detected 610. The detected episode may be, for example, arate-based or other anomaly for which discrimination and/orcharacterization is desired. Information from the detected episode 610is compared or matched 620 to one or more NSR/SVT templates to determinecorrespondence with the template. One method of determining that acardiac signal may match, or correspond, to a template utilizes acorrelation algorithm or other form of comparison. For example,morphological features of a signal may be measured with respect toamplitudes, inflection points, curvatures, timing of features, or otherattributes. Characteristics such as timing onset, stability, variabilityof intervals between features of successive heartbeats, rates, and othercharacteristics may be included as part of a template. A template mayinclude acceptable ranges and/or acceptable statistics of measurablefeatures.

As an example, useful for illustrative purposes but not limiting,consider that morphological features are used to match 620 a set oftemplates. If the episode 610 matches or corresponds 620 to one or moreNSR/SVT templates, then the episode is determined to not require therapy625.

If the episode 610 does not match 620 to one or more NSR/SVT templates,then the morphological features of the episode 610 are compared 630 to aset of VT/VF templates. If the morphological features do not match anyNSR/SVT templates 620 or any VT/VF templates 630, then a default therapy640 is attempted, and a new VT template may be established 650. If amaximum number of templates have been reached, the method 600 may erasea template by overwriting it with new information from the latestepisode 610.

In accordance with embodiments of devices that provide communicationswith a patient-external device, a clinician may be queried to determineif a new template is desired, or if an existing template needs to beupdated or erased. This may be accomplished in coordination with anarrhythmia logbook of a PIMD during patient follow-up. Features oflogbooks useful for PIMDs in accordance with the present invention arefurther described in commonly owned U.S. Publication Nos. 2005/0080348and 2005/0085738, which are hereby incorporated herein by reference.Patient information acquired by such logbook systems may be incorporatedor associated with VT (or atrial) templates.

In other embodiments, a template is selected for replacement using acriterion such as: templates older than a predetermined age; the oldestout of all current templates; templates that have not corresponded to anarrhythmia for a pre-determined time period; templates selected forreplacement by an advanced patient management (APM) system via manualselection or via algorithmic selection; templates that have correspondedleast frequently to an arrhythmia relative to other templates; templateshaving a pre-determined association (e.g., a drug regimen association);templates having an associated heart-rate or other identified featuressimilar to other templates; or other template selection criteria.

After the new template 650 is established, patient history informationmay be acquired to fill in the necessary information of the template forfuture episodes. If an existing template is matched 630, or a newtemplate 650 has been established, a check 670 determines if theprevious therapy was successful and/or satisfactory. The previoustherapy may be, for example, a therapy delivered in response to a priorepisode, or a therapy previously attempted for the current episode. Ifthe check 670 determines that the therapy was unsatisfactory, such as bynot successfully terminating an arrhythmia, or by accelerating the heartrhythm, then an alternate ATP therapy 680 may be attempted.

If all alternative ATP therapies 680 have been attempted, then acardioversion or defibrillation shock 695 is delivered to treat theepisode 610, and the template is updated with information 660 such thatthe next time a cardiac signal matches that template, ATP will not beattempted, and shock therapy will be chosen. If alternative ATPtherapies 680 have not been tried, then an attempt 690 is made todetermine if a therapy less extreme (e.g., less painful) thancardioversion/defibrillation may correct the episode 610, and anothercheck 670 is performed. An update 660 will occur to retain the mostrecent satisfactory treatment selection determined by the check 670,such that for any future episode 610 that corresponds to the template,treatment selection information will be provided for the treatmentselection process.

If multiple templates are matched to the episode, then an arbitrationprocess may be initiated to determine which of the multiple templates isto be selected. For example, the most recently used matched templatewith a successful therapy may be selected as the “best” template. Othercriteria may be used to select between multiple matched templates, suchas using the template most frequently matched to arrhythmia episodes inthe past, the template having the closest rate to the current episode,the template having the highest treatment satisfaction with respect topast arrhythmia episodes, the template having the least aggressivesuccessful treatment, or other useful criterion. The method 600 providesthat a PIMD incorporating the method 600 will automatically incorporateinformation about that patient's prior treatment efficacy, andautomatically re-program the PIMD on an episode-by-episode basis.

FIG. 7 is a block diagram illustrating a methodology for determiningpatient therapy response information in accordance with embodiments ofthe invention. An arrhythmia treatment methodology 700 may be used toassociate a therapy with a template in accordance with embodiments ofthe present invention. The template 720 may be associated with anarrhythmia event 710, such as by corresponding to or matching thetemplate 720, or as having been used to generate the template 720. Atherapy 730 is associated with the template 720.

The therapy 730 may have been associated with the template 720 aftersuccessfully treating the arrhythmia event 710. The therapy 730 may havebeen delivered to a prior episode, may have been algorithmicallyselected via an APM system, may have been selected by a physician usinga programmer or APM system, or may have been delivered to the currentarrhythmia event 710. For example, an APM system may maintain a databaseof templates from patients other than the patient experiencing thearrhythmia event 710. The APM system may find a corresponding template,and determine what was the most satisfactory therapy for treatingarrhythmias in other patients. The APM system may then select that mostsuccessful therapy as the therapy to associate with the template 720.

The therapy 730 associated with the template 720 may be a single therapyor include a number of therapies, as is shown in FIG. 7 as therapies740. Therapies 740 include one or more shock therapies 742, which maybe, for example, a maximum energy shock available from a PIMD, such as a31 Joule shock (e.g., mono-phasic, bi-phasic, or tri-phasic shocks).Therapies 740 may also include one or more cardioversion therapies 744,which may be, for example, a lower energy shock, such as a 14 Jouleshock. Therapies 740 may also include several ATP therapies, such asATP1 therapy 748, ATP2 therapy 747, ATP3 therapy 746, and ATP4 therapy745. The ATP therapies 745-748 may be all different therapies having thesame energy level, for example. An aggressiveness level 750 indicatesthat ATP therapies 745-748 are considered less aggressive than thecardioversion therapy 744, which is less aggressive than shock therapy742.

When a template is originated, an initial arrhythmia may be treated witha lower aggression therapy first, and different therapies, increasing inaggressiveness, may be attempted until a therapy is successful attreating the arrhythmia. The lowest aggressiveness therapy thatsuccessfully treats the arrhythmia may then be associated with thetemplate for future reference. This corresponds to a hierarchicalapproach, where therapies are attempted in an ordered fashion accordingto an aggressiveness hierarchy. A method for generating and selectinghierarchies of therapies is described in U.S. Publication No.2004/0167579A1, which is hereby incorporated herein by reference.

In other embodiments, a more aggressive therapy may be used when acardiac waveform is sensed that does not match or correspond to anytemplate, and the waveform may be saved or transmitted for assessment bya clinician to determine if a template should be made, or if anothertherapy should be associated with that type of cardiac waveform. Forexample, upon initial determination of a new arrhythmia, a high-energyshock, an initial ATP therapy, or other default therapy, may be used andthe cardiac waveform may be designated for review to determine whichtherapy, if any, should be associated with subsequent correspondingarrhythmias.

In other embodiments, a heuristic approach is used where no hierarchy isestablished. For example, the last therapy delivered may be repeated, ora therapy may be randomly selected from available therapies until asatisfactory therapy is determined. Satisfaction with a therapy mayinclude parameters other than just effectiveness such as, for example,time to effectiveness, patient pain, patient loss of consciousness, orother satisfaction criteria.

FIG. 8 is a flow chart illustrating a method 800 of template selectionand generation for therapy selection using patient response informationin accordance with embodiments of the invention. According to thisembodiment, templates are established by a physician selecting a cardiacwaveform for template creation after reviewing a logbook of arrhythmiaepisodes and treatments. An arrhythmia is detected 820 using a cardiacwaveform signal. The waveform is compared 830 to each template in thetemplate list, if any. If the cardiac waveform corresponds to a template840, the template may then be used for therapy selection 850, based onpatient therapy history information associated with the template, asdescribed above.

If the detected waveform does not correspond to the template 840, thewaveform is compared to the next template until all templates have beencompared 860 to the cardiac waveform. If none of the templates 840correspond to the cardiac waveform, the arrhythmia is treated 862.Treatment 862 may be performed using the method 700, for example.Alternatively, the arrhythmia may be treated using a cardioversionand/or defibrillation methodology, or other predetermined defaulttreatment. The cardiac waveform, and any associated information, such astreatment history, and/or other sensor information is recorded 864, suchas by using a memory or logbook feature.

The cardiac waveform and associated information is then reviewed by aclinician, such as a physician 866. The physician 866 may selectparticular recorded waveforms for template generation 870. The selectedwaveforms then have templates formed 870, and a therapy is associatedwith the template. When reviewing the recording 864, the physician mayselect or eliminate from consideration one or more therapies 872 forassociation with the template. For example, the physician may determinethat a defibrillation was performed on a cardiac waveform that may betreated by ATP. The physician may select ATP therapy as the associatedtherapy for the template 870, such that the next cardiac waveform thatmatches or corresponds to the template 870 is treated with ATP therapy.The physician may also select an order of multiple therapies to try, forexample.

The physician may select an ATP therapy of similar aggression, butdifferent coupling interval. The coupling interval is the point in timeduring the cardiac cycle at which the pacing pulse should be delivered.A typical coupling interval is 80%, with the pacing pulse delivered at atime predicted to be 80% between the last R wave and the next R wave.ATP with a coupling interval of 70% may deliver the same energy to thepatient as ATP with a coupling interval of 80%. However, shortercoupling intervals are considered to be more aggressive, as there ismore risk that the pacing pulse could accelerate the rhythm instead ofterminating the rhythm.

Other information may also be associated with the template, such aspatient medication levels, patient activity information, and otherinformation provided by the physician that may provide improveddiscrimination for therapy delivery selection. The physician may providethe information during a follow-up office visit, using a programmer, forexample. The physician or a clinician may also perform the method 800remotely, such as by using an advanced patient management (APM) system868 as will be described below. In other embodiments, the APM system mayincorporate an artificial intelligence system or other programming toremotely perform methods of template generation, initialization,updating, therapy association, and/or selection in accordance with thepresent invention.

Devices and methods useful for determining or acquiring information thatmay be associated with templates in accordance with embodiments of thepresent invention are further described in commonly owned co-pendingU.S. Publication Nos. 2003/0109902, 2005/0081847, and 2006/0047333,which are hereby incorporated herein by reference.

Referring now to FIG. 9, a PIMD of the present invention may be usedwithin the structure of an APM system 1300. The APM system 1300 allowsphysicians and/or other clinicians to remotely and automatically monitorcardiac and respiratory functions, as well as other patient conditions.The APM system 1300 may also be used to provide information to the PIMDfor incorporation into templates, such as medication information orother patient information useful in accordance with the presentinvention. The APM system 1300 may also be used to select portions ofcardiac waveforms for which templates are desired. The APM system 1300may also be used to select or eliminate therapies associated withtemplates. In one example, a PIMD implemented as a cardiac pacemaker,defibrillator, or resynchronization device may be equipped with varioustelecommunications and information technologies that enable real-timedata collection, diagnosis, and treatment of the patient.

Various PIMD embodiments described herein may be used in connection withadvanced patient management. Methods, structures, and/or techniquesdescribed herein, which may be adapted to provide for remotepatient/device monitoring, diagnosis, therapy, or other APM relatedmethodologies, may incorporate features of one or more of the followingreferences: U.S. Pat. Nos. 6,221,011; 6,270,457; 6,277,072; 6,280,380;6,312,378; 6,336,903; 6,358,203; 6,368,284; 6,398,728; and 6,440,066,which are hereby incorporated herein by reference.

As is illustrated in FIG. 9, the medical system 1300 may be used toimplement template generation, template updating, templateinitialization, template selection, patient measuring, patientmonitoring, patient diagnosis, patient therapy, therapy selection,and/or therapy elimination in accordance with embodiments of theinvention. The medical system 1300 may include, for example, one or morepatient-internal medical devices 1310, such as a PIMD, and one or morepatient-external medical devices 1320, such as a monitor or signaldisplay device. Each of the patient-internal 1310 and patient-external1320 medical devices may include one or more of a patient monitoringunit 1312, 1322, a diagnostics unit 1314, 1324, and/or a therapy unit1316, 1326.

The patient-external medical device 1320 performs monitoring, and/ordiagnosis and/or therapy functions external to the patient (i.e., notinvasively implanted within the patient's body). The patient-externalmedical device 1320 may be positioned on the patient, near the patient,or in any location external to the patient.

The patient-internal and patient-external medical devices 1310, 1320 maybe coupled to one or more sensors 1341, 1342, 1345, 1346, patientinput/trigger devices 1343, 1347, and/or other information acquisitiondevices 1344, 1348. The sensors 1341, 1342, 1345, 1346, patientinput/trigger devices 1343, 1347, and/or other information acquisitiondevices 1344, 1348 may be employed to detect conditions relevant to themonitoring, diagnostic, and/or therapeutic functions of thepatient-internal and patient-external medical devices 1310, 1320.

The medical devices 1310, 1320 may each be coupled to one or morepatient-internal sensors 1341, 1345 that are fully or partiallyimplantable within the patient. The medical devices 1310, 1320 may alsobe coupled to patient-external sensors positioned on, near, or in aremote location with respect to the patient. The patient-internal andpatient-external sensors are used to sense conditions, such asphysiological or environmental conditions, that affect the patient.

The patient-internal sensors 1341 may be coupled to the patient-internalmedical device 1310 through one or more internal leads 1353. Stillreferring to FIG. 9, one or more patient-internal sensors 1341 may beequipped with transceiver circuitry to support wireless communicationsbetween the one or more patient-internal sensors 1341 and thepatient-internal medical device 1310 and/or the patient-external medicaldevice 1320. The patient-internal sensors 1345 may be coupled to thepatient-external medical device 1320 through a wireless connection 1359,and/or using communications between the patient-internal medical device1310 and the patient-external medical device 1320, or may be coupledusing a wire or other communications channel.

The patient-external sensors 1342 may be coupled to the patient-internalmedical device 1310 through one or more internal leads 1355.Patient-external sensors 1342 may communicate with the patient-internalmedical device 1310 wirelessly. Patient-external sensors 1342 may becoupled to the patient-external medical device 1320 through one or moreleads 1357 or through a wireless link.

In an embodiment of the present invention, the patient-external medicaldevice 1320 includes a visual display configured to concurrently displaynon-electrophysiological signals and intracardiac electrogram signals.For example, the display may present the information visually. Thepatient-external medical device 1320 may also, or alternately, providesignals to other components of the medical system 1300 for presentationto a clinician, whether local to the patient or remote to the patient.

Referring still to FIG. 9, the medical devices 1310, 1320 may beconnected to one or more information acquisition devices 1344, 1348,such as a database that stores information useful in connection with themonitoring, diagnostic, or therapy functions of the medical devices1310, 1320. For example, one or more of the medical devices 1310, 1320may be coupled through a network to a patient information server 1330.

The input/trigger devices 1343, 1347 are used to allow the physician,clinician, and/or patient to manually trigger and/or transferinformation to the medical devices 1310, 1320 and/or from the APM system1340 and/or patient-external medical device 1320 back to thepatient-internal device 1310. The input/trigger devices 1343, 1347 maybe particularly useful for inputting information concerning patientperceptions, such as a perceived cardiac event, how well the patientfeels, and other information not automatically sensed or detected by themedical devices 1310, 1320. For example, the patient may trigger theinput/trigger device 1343 upon perceiving a cardiac event. The triggermay then initiate the recording of cardiac signals and/or other sensorsignals in the patient-internal device 1310. Later, a clinician maytrigger the input/trigger device 1347, initiating the transfer of therecorded cardiac and/or other signals from the patient-internal device1310 to the patient-external device 1320 for display and diagnosis.

In one embodiment, the patient-internal medical device 1310 and thepatient-external medical device 1320 may communicate through a wirelesslink between the medical devices 1310, 1320. For example, thepatient-internal and patient-external devices 1310, 1320 may be coupledthrough a short-range radio link, such as Bluetooth, IEEE 802.11, and/ora proprietary wireless protocol. The communications link may facilitateuni-directional or bi-directional communication between thepatient-internal 1310 and patient-external 1320 medical devices. Dataand/or control signals may be transmitted between the patient-internal1310 and patient-external 1320 medical devices to coordinate thefunctions of the medical devices 1310, 1320.

In another embodiment, patient data may be downloaded from one or moreof the medical devices periodically or on command, and stored at thepatient information server 1330. The physician and/or the patient maycommunicate with the medical devices and the patient information server1330, for example, to acquire patient data or to initiate, terminate, ormodify recording and/or therapy.

The data stored on the patient information server 1330 may be accessibleby the patient and the patient's physician through one or more terminals1350, e.g., remote computers located in the patient's home or thephysician's office. The patient information server 1330 may be used tocommunicate to one or more of the patient-internal and patient-externalmedical devices 1310, 1320 to provide remote control of the monitoring,diagnosis, and/or therapy functions of the medical devices 1310, 1320.

In one embodiment, the patient's physician may access patient datatransmitted from the medical devices 1310, 1320 to the patientinformation server 1330. After evaluation of the patient data, thepatient's physician may communicate with one or more of thepatient-internal or patient-external devices 1310, 1320 through an APMsystem 1340 to initiate, terminate, or modify the monitoring,diagnostic, and/or therapy functions of the patient-internal and/orpatient-external medical systems 1310, 1320.

In another embodiment, the patient-internal and patient-external medicaldevices 13 10, 1320 may not communicate directly, but may communicateindirectly through the APM system 1340. In this embodiment, the APMsystem 1340 may operate as an intermediary between two or more of themedical devices 1310, 1320. For example, data and/or control informationmay be transferred from one of the medical devices 1310, 1320 to the APMsystem 1340. The APM system 1340 may transfer the data and/or controlinformation to another of the medical devices 1310,1320.

In one embodiment, the APM system 1340 may communicate directly with thepatient-internal and/or patient-external medical devices 1310, 1320. Inanother embodiment, the APM system 1340 may communicate with thepatient-internal and/or patient-external medical devices 1310, 1320through medical device programmers 1360, 1370 respectively associatedwith each medical device 1310, 1320. As was stated previously, thepatient-internal medical device 1310 may take the form of an implantablePIMD.

Medical devices and methods that select tachyarrhythmia therapy based onprevious patient therapy responses in accordance with the presentinvention may be used in combination with methods of tachyarrhythmiadiscrimination using arrhythmia memory, which is further described incommonly-owned co-pending U.S. Publication No. 2006/0111643, which ishereby incorporated herein by reference, and/or in combination withmethods of generating templates based on previous patient therapyresponses, which is further described in commonly-owned co-pending U.S.Publication No. 2006/0111747, which is hereby incorporated herein byreference.

Various modifications and additions can be made to the preferredembodiments discussed hereinabove without departing from the scope ofthe present invention. Accordingly, the scope of the present inventionshould not be limited by the particular embodiments described above, butshould be defined only by the claims set forth below and equivalentsthereof.

1. A method, comprising: providing one or more templates representativeof one or more of a patient's past tachyarrhythmia events, the one ormore templates associated with a therapy to treat tachyarrhythmiaevents; detecting a cardiac waveform; and if the cardiac waveformcorresponds to a particular template of the one or more templates,determining if a previous therapy associated with the particulartemplate was satisfactory in terminating a past tachyarrhythmia eventassociated with the particular template, and, if determinedunsatisfactory, eliminating the previous therapy as an option fortreating a subsequent tachyarrhythmia event associated with theparticular template and associating the particular template with a newtherapy.
 2. The method of claim 1, wherein if the previous therapy wasan antitachycardia pacing therapy determined to be unsatisfactory interminating the past tachyarrhythmia event, eliminating delivery of theantitachycardia pacing therapy as an option for treating a subsequenttachyarrhythmia event and associating one or more of a cardioversion, adefibrillation therapy, or an alternate anti-tachycardia pacing therapywith the particular template.
 3. The method of claim 1, wherein thecorrespondence between the cardiac waveform and the particular templateis a correspondence in terms of morphology.
 4. The method of claim 1,wherein the correspondence between the cardiac waveform and theparticular template is a correspondence in terms of timing.
 5. Themethod of claim 1, wherein the correspondence between the cardiacwaveform and the particular template is a correspondence in terms of a)drug regimen and morphology or b) drug regimen and timing.
 6. The methodof claim 1, comprising adding a new template to the one or moretemplates by replacing an oldest template of the one or more templateswith the new template.
 7. The method of claim 1, comprising associatingone or more of medication information, neural activity information,patient activity information, hemodynamic status information, cardiactissue impedance information, and transthoracic impedance informationwith the one or more templates.
 8. The method of claim 1, comprisingdeleting a particular template of the one or more templates if theparticular template is older than a predetermined age, or has notcorresponded to a cardiac waveform for a predetermined time, or hascorresponded to past arrhythmias least frequently relative to othertemplates, or represents a heart-rate similar to other existingtemplates.
 9. The method of claim 1, comprising deleting a particulartemplate of the one or more templates if the particular template isassociated with a drug regimen that no longer matches the patient'scurrent drug regimen.
 10. The method of claim 1, wherein the detectedcardiac waveform is indicative of an arrhythmia in the ventricles, ofventricular or supra-ventricular origin.
 11. The method of claim 1,wherein the detected cardiac waveform is indicative of an arrhythmia inthe atria.
 12. The method of claim 1, further comprising arbitratingbetween two or more templates if the cardiac waveform corresponds to twoor more templates.
 13. The method of claim 1, further comprising, if thecardiac waveform corresponds to two or more templates: selecting atemplate of the two or more templates associated with a treatmentsatisfactory in terminating the past tachyarrhythmia event, anddelivering its associated tachyarrhythmia therapy; or selecting a mostrecently used or generated template associated with a treatmentsatisfactory in terminating the past tachyarrhythmia event, anddelivering its associated tachyarrhythmia therapy; or selecting the mostfrequently matched template associated with a treatment satisfactory interminating the past tachyarrhythmia event, and delivering itsassociated tachyarrhythmia therapy; or selecting the template associatedwith a treatment satisfactory in terminating the past tachyarrhythmiaevent whose rate information most closely corresponds to the detectedcardiac waveform, and delivering its associated tachyarrhythmia therapy;or selecting the template associated with one or more of a patient'sdrug regimen, neural activity, patient activity, hemodynamic state,transthoracic impedance, and cardiac tissue impedance similar to thepatient's current status.
 14. The method of claim 1, wherein the newtherapy comprises an anti-tachycardia pacing therapy of substantiallyequivalent aggression in terms of energy or coupling interval.
 15. Themethod of claim 1, wherein the new therapy comprises an anti-tachycardiapacing therapy of greater aggression in terms of energy or couplinginterval.
 16. The method of claim 1, wherein the new therapy comprises acardioversion or defibrillation therapy.
 17. A medical system,comprising: a cardiac therapy system configured to deliver a cardiactherapy to a patient; a detector system configured to detect a cardiacwaveform associated with a tachyarrhythmia; and a template processorcoupled to the detector system and the cardiac therapy system, thetemplate processor configured to provide one or more templatesrepresentative of one or more of a patient's past tachyarrhythmiaevents, the one or more templates associated with a therapy to treattachyarrhythmia events, and, if the cardiac waveform corresponds to aparticular template of the one or more templates, the template processorconfigured to determine if a previous therapy associated with theparticular template was satisfactory in terminating a pasttachyarrhythmia event corresponding to the particular template, and ifdetermined unsatisfactory, eliminate the previous therapy as an optionfor treating a subsequent tachyarrhythmia event associated with theparticular template and associate the particular template with a newtherapy.
 18. The system of claim 17, wherein the cardiac therapy systemis configured to deliver an anti-tachycardia pacing therapy to thepatient to treat the tachyarrhythmia and determine one or both of theeffectiveness and satisfaction of the anti-tachycardia pacing therapy.19. The system of claim 17, comprising a patient activity sensorconfigured to provide patient activity information associated withtachyarrhythmia episodes to the template processor.
 20. The system ofclaim 17, comprising a neural activity sensor configured to providepatient neural activity information associated with tachyarrhythmiaepisodes to the template processor.
 21. The system of claim 17,comprising a transthoracic impedance sensor configured to providepatient transthoracic impedance information associated withtachyarrhythmia episodes to the template processor.
 22. The system ofclaim 17, comprising an accelerometer configured to provide accelerationinformation associated with tachyarrhythmia episodes to the templateprocessor.
 23. The system of claim 17, comprising a cardiac tissueimpedance sensing system configured to provide patient cardiac tissueimpedance information associated with tachyarrhythmia episodes to thetemplate processor.
 24. The system of claim 17, comprising a hemodynamicstatus sensor configured to provide patient hemodynamic statusinformation associated with tachyarrhythmia episodes.